2he  Motion  Picture  Theater 
Interior  Illumination  and 
the  Selection  of  the  Screen 


Eastman  Kodak  Company, 

Rochester,  N.  Y. 


The  Motion  Picture  Theater 
Its  Interior  Illumination  and 
the  Selection  of    the   Screen 


A   Booklet  for   Motion    Picture 
Theater  Owners  and  Alanagers 


Eastman  Kodak  Company 
Rochester,  N.  Y. 

1922 


Introduction 

THE  motion  picture  theater  did  not  spring  at  once  into 
popularity,  due,  in  part,  to  the  fact  that  Httle  attention 
was  given  to  the  comfort  of  the  spectators.  In  the  early 
days,  the  pictures  were  usually  exhibited  in  a  stuffy  im- 
provised hall  and  in  total  darkness.  After  the  arrival  of 
the  motion  picture  theater  with  its  more  pleasing  and  com- 
fortable surroundings,  the  number  of  persons  attending  the 
theater  increased  enormously.  In  the  modern  theater  every 
detail  of  decoration,  ventilation  and  temperature  regulation 
has  been  most  carefully  worked  out. 

The  public  will  invariably  prefer  to  patronize  the  modern 
theater  in  which  the  optical  and  physical  comforts  have 
been  looked  after.  It  will  fill  the  up-to-date  picture  house 
to  capacity  and  at  good  prices  even  when  another  theater, 
where  the  surroundings  are  not  pleasant,  is  showing  the 
same  picture  for  less  money.  People  may  be  easily  attracted 
to  a  theater  for  the  first  time  by  a  good  picture.  They  will 
come  again  if  they  viewed  the  picture  in  comfort. 

When  Mr.  Eastman,  in  connection  with  his  gift  of  a 
school  of  music  to  the  people  of  the  City  of  Rochester,  con- 
ceived the  idea  of  an  endowed  motion  picture  theater,  it 
was  found  that  little  attention  had  been  paid  in  the  past 
to  the  scientific  illumination  of  the  interior  of  the  theater, 
or  to  the  choice  of  a  suitable  projection  screen.  It  was  Mr. 
Eastman's  wish  that  this  theater  should  offer  the  best  sur- 
roundings for  the  exhibition  of  the  pictures  and  should  be 
a  model  theater  in  every  detail.  Consequently,  the  prob- 
lem was  turned  over  to  the  Kodak  Research  Laboratory  to 
find  the  maximum  of  permissible  lighting  of  the  interior  of 
the  theater  and  to  choose  the  screen  best  suited  to  the 
installation. 


The  results  of  these  tests,  it  is  believed,  will  be  of  very 
great  interest  to  every  motion  picture  theater  owner,  archi- 
tect, and  engineer.  The  question  of  correct  lighting  of  the 
theater  and  screen  is  of  as  much  importance  in  the  motion 
picture  theater  as  the  acoustic  properties  of  the  opera  house, 
concert  hall  or  the  theater  devoted  to  the  spoken  drama. 
This  booklet  is  published  in  order  that  the  lighting  condi- 
tions may  be  raised  to  the  high  standard  already  set  in  the 
other  details  of  the  theater  and  in  the  excellence  of  the 
screen  offering. 

It  is  as  important  that  theater  patrons  be  relieved  from 
tired  eyes  as  that  they  should  have  comfortable  seats,  good 
ventilation  and  satisfying  music.  They  go  to  see  the  pic- 
tures for  rest  and  relaxation  as  well  as  for  amusement.  If 
they  go  home  from  the  theater  with  all  of  their  senses 
pleased,  they  will  come  back  to  that  theater  again  and 
again. 

The  Kodak  Research  Laboratory  is  peculiarly  adapted 
to  handling  problems  connected  with  light  and  lighting. 
It  is  light  that,  by  affecting  the  sensitive  materials,  makes 
the  negative.  It  is  light  that  prints  the  positive  from  the 
negative.  Light  is  the  basis  of  photography  and  so  our 
Laboratory  men  know  light  as  no  other  group  of  men  in 
the  world  know  it  and  they  have  at  their  command  all  the 
apparatus  for  conducting  the  most  exhaustive  experiments. 
And  when  a  new  problem  comes  along  that  requires  some 
hitherto  unknown  piece  of  apparatus  for  its  solving,  they 
design  and  construct  whatever  may  be  needed. 

There  was  a  work  to  be  accomplished  in  improving  the 
lighting  conditions  in  motion  picture  theaters  and  in  pro- 
viding a  more  intelligent  selection  and  use  of  screens.  The 
Kodak  Research  Laboratory  had  both  the  men  and  the 
equipment  for  the  work.  And  so  there  was  turned  over  to  it 
the  task  of  investigating  conditions  and  carrying  out  a  series 
of  experiments,  the  results  of  which  should  be  of  definite 
benefit  to  the  entire  motion  picture  industry. 


There  was  a  vast  amount  of  work  accomplished  and  the 
conclusions  that  were  arrived  at  as  a  result  of  that  work 
are  contained  in  this  little  book.  Even  now  we  do  not  feel 
that  all  of  the  lighting  problems  are  solved  for  all  time,  but 
we  do  feel  that  the  subject  has  been  intelligently  covered. 
However,  new  problems  will  be  constantly  arising  and  we 
shall  gladly  use  our  Laboratory  resources  in  helping  you  to 
solve  those  problems — not  merely  in  a  general  way  but  in 
a  specific  way  if  you  ask  for  our  help. 

Eastman  Kodak  Company, 

Rochester,  X.  Y. 


The  Illumination  of  the  Interior 

IN  the  early  days  of  the  motion  picture  theater,  it  was 
customary  to  present  the  pictures  in  a  room  containing 
practically  no  illumination  except  what  resulted  from  reflec- 
tion at  the  screen.  This  procedure  may  have  been  justified 
to  a  certain  extent  at  that  time  because  the  light  used  for 
projecting  the  picture  was  very  weak,  making  it  necessary 
to  exclude  practically  all  the  light  from  the  room  in  order 
that  the  screen  might  appear  of  satisfactory  brightness. 
With  improvements  in  the  projection  apparatus  and  in  the 
quality  of  the  photographic  materials,  the  brightness  of  the 
picture  itself  has  been  increased  until  it  is  of  relatively  high 
intensity.  Following  this,  there  has  been  some  increase  in 
the  illumination  of  the  interior  of  the  theater.  The  higher 
screen  brightness  naturally  permits  more  interior  illumina- 
tion without  seriously  interfering  with  the  picture. 

The  desirability  of  comfortably  lighting  the  theater  is 
at  once  apparent  provided  it  can  be  done  without  loss  of 
quality  in  the  picture.  It  is  hardly  necessary  to  enumerate 
the  objections  to  the  use  of  poorly  lighted  theaters.  The 
difficulty  encountered  by  persons  entering  the  theater  in 
finding  their  way  to  unoccupied  seats,  and  the  strain  placed 
upon  the  eyes  by  the  sudden  transition  from  the  dark  in- 
terior to  the  brightly  lighted  exterior  when  leaving,  are 
familiar  to  everyone.  Furthermore,  in  a  poorly  lighted 
theater,  it  is  quite  impossible  for  the  management  to  super- 
vise adequately  the  conduct  of  individuals;  a  fact  which 
has  lead  to  no  little  criticism  of  the  motion  picture  theater. 
More  serious  than  any  of  these,  however,  is  the  tax  placed 
upon  the  eyes  when  viewing  a  bright  screen  in  a  dark  theater. 
The  eyes  become  adjusted  to  brightness  conditions  just  as 
a  runner  gets  his  second  wind  when  his  pace  has  become 
adjusted  to  his  physical  ability.  The  ideal  condition  for 
viewing  the  motion  picture  screen  occurs  when  the  eyes 
have  become  adapted   to   the  average  brightness  of  the 


screen.  This  is  usually  impossible  since  the  screen  fills 
only  a  small  fraction  of  the  whole  field  of  view  and  the 
remainder  of  the  field  is  very  dark.  Because  of  this,  the 
eyes  are  forced  to  view  a  bright  screen  to  which  they  can 
never  become  adapted.  In  other  words,  the  eyes  under  the 
above  conditions  are  in  the  same  state  of  distress  as  the 
runner  before  he  gets  his  second-wind,  but  in  the  case  of 
the  eyes  the  condition  continues  indefinitely.  The  remedy 
is,  of  course,  to  increase  the  illumination  of  the  interior  of 
the  theater.  The  first  phase  of  the  problem  undertaken 
by  the  Kodak  Research  Laboratory  was  the  determination 
of  the  conditions  of  interior  illumination  which  would  afTord 
the  maximum  of  comfort  for  the  audience  without  impair- 
ing the  quality  of  the  picture. 

In  order  to  make  practical  tests  of  illumination,  a  pro- 
jection booth  and  a  projection  machine  were  installed  in 
a  room  in  the  laboratory.  A  projection  screen  of  an  ord- 
inary type  was  placed  at  one  end  of  the  room.  The  room 
was  about  forty-two  feet  long  and  the  ceiling  of  the  room 
was  white,  while  the  walls  were  a  medium  tone  of  buff.  A 
lighting  fixture  was  suspended  from  the  ceiling  from  brackets 
in  such  a  way  that  the  position  of  the  fixture  in  the  room, 
the  angle  of  inclination  and  the  distance  from  the  ceiling 
could  be  varied  in  almost  every  conceivable  manner.  The 
fixture  itself  was  of  the  indirect  type  so  arranged  that  the 
direct  rays  from  the  lamps  could  strike  only  on  the  ceiling 
and  rear  wall  of  the  room.  The  electric  current  in  the  arc 
of  the  projection  machine  was  adjusted  so  that  the  bright- 
ness of  the  screen  with  the  machine  running,  but  without 
a  film,   was   20  apparent   foot-candles*  which   is  slightly 

*Jiist  as  the  candle  power  is  the  unit  of  light  intensity,  the  foot- 
candle  is  the  unit  of  the  illumination  produced.  Thus,  a  16  candle- 
power  lamp  one  foot  away  from  the  screen  would  produce  an  illumina- 
tion of  16  foot-candles.  A  i2  candle-power  lamp  would  produce  an 
illumination  of  32  foot-candles.  By  the  20-ft.  candles  given  above  is 
meant  that  the  light  coming  from  the  projection  machine  illuminates 
the  screen  to  the  same  brightness  as  a  20  candle-power  lamp  would 
illuminate  a  portion  of  the  screen  placed  one  foot  from  the  lamp. 


higher  than  an  average  brightness  as  measured  in  a  num- 
ber of  motion  picture  theaters. 

With  conditions  estabhshed  which  were  similar  to  those 
in  a  motion  picture  theater,  the  research  laboratory  made 
many  trials  to  determine  the  most  suitable  lighting  arrange- 
ment. The  number  of  lights  in  the  fixture  and  the  position 
of  the  fixture  in  the  room  were  altered  in  every  way  possible. 
At  last,  a  condition  was  found  where  the  illumination  seemed 
to  be  better  than  any  other.  The  general  room  illumination 
was  such  that  a  person  entering  the  room  from  the  bright 
sunshine  could  see  immediately  all  details  of  furniture  about 
the  room  and  after  a  period  of  not  more  than  one  or  two 
minutes,  could  read  ordinary  printed  matter.  Indeed,  the 
facility  with  which  print  could  he  read  would  make  it  entirely 
feasible  to  sell  advertising  space  on  programs. 

To  be  sure  that  the  quality  of  the  picture  was  not 
impaired  by  this  scheme  of  lighting,  several  persons  experi- 
enced in  the  judging  of  the  photographic  quality  were  asked 
to  express  their  opinions.  These  observers  were  unanimous 
in  the  decision  that,  not  only  was  the  photographic  quality 
of  the  picture  fully  as  good,  but  that  the  effect  was  more 
pleasing  and  resulted  in  greater  visual  comfort.  An  impor- 
tant point  noted  was  that  much  less  shock  was  experienced 
by  the  eyes  when  the  screen  brightness  was  suddenly 
changed  by  the  appearance  of  a  title,  and  further,  that  the 
slight  flicker  due  to  a  lack  of  precise  shutter  adjustment 
was  less  noticeable.  On  the  whole,  the  arrangement  was 
considered  satisfactory  by  all  the  spectators. 

Having  found  what  seemed  to  be  the  best  lighting  con- 
ditions, the  illumination  was  measured  at  many  different 
points  in  the  room.  This  can  be  done  by  means  of  a  small 
portable  instrument*  which  can  be  used  to  measure  the 


*The  instrument  used  in  this  work  was  a  Macbeth  Illuminometer 
made  by  the  Leeds  8c  Northup  Company,  Philadelphia,  Pa.  It  is 
essentially  a  portable  photometer  which  is  calibrated  to  measure  illum- 
ination. In  use,  an  opal  glass  test  plate  is  placed  at  the  point  where 
the  illumination  is  to  be  measured.     The  instrument  is  then  pointed 


illumination  at  as  many  diflPerent  places  as  desired.  From 
the  values  obtained,  an  illumination  engineer  is  able  to 
duplicate  this  condition  in  any  theater.  Obviously,  spe- 
cific instructions  for  theater  lighting  can  not  be  laid  down 
because  every-  theater  is  more  or  less  a  problem  in  itself. 
Such  factors  as  the  size,  the  architectural  details,  use  of 
cornices  and  arches,  the  reflecting  power  of  various  ceiling 
and  wall  surfaces  have  to  be  taken  into  any  computation. 
Certain  decorative  schemes,  especially  of  ceiling,  may  also 
have  to  be  worked  out  in  order  to  make  the  lighting  most 
effective.  Since  the  lamps  must  in  general  be  placed  close 
to  the  ceiling,  certain  regions  require  a  low  reflecting  power 
and  others  a  high  reflecting  power.  All  of  these  factors 
may  be  taken  into  account,  however,  and  with  close  co- 
operation between  the  lighting  engineer  and  the  designer 
of  the  decorative  scheme,  a  highly  satisfacton.-  arrange- 
ment may  be  chosen. 

To  show  the  improvement  which  might  be  brought 
about  in  a  theater  in  which  the  lighting  system  was  already 
installed,  the  Kodak  experts  designed  a  scheme  of  illumina- 
tion for  a  small  theater  used  for  the  exhibition  of  motion 
pictures.  The  results  obtained  in  the  experimental  room 
were  made  the  basis  of  the  new  calculations.  The  details 
were  worked  out  to  give  ver\-  nearly  the  same  amount  of 
general  illumination  as  the  experimental  room.  In  this 
case  also,  the  results  were  found  to  be  satisfactor\-  and  the 
general  effect  more  pleasing  with  less  strain  on  the  eyes. 
The  general  conclusion  which  can  be  drawn  from  these 
experiments  is  that  a  relatively  large  amount  of  general 
illumination  may  exist  in  a  motion  picture  theater  without 
interfering  with  the  projected  picture  provided  the  illumi- 
nation is  properly  distributed. 


at  the  test  plate  and  by  changing  the  position  of  a  small  incandescent 
lamp  in  the  instrument,  a  balance  in  intensity  is  secured  between  the 
light  from  the  test  plate  and  the  light  from  the  lamp.  The  illumina- 
tion can  then  be  read  directly  in  foot-candles  on  the  scale  of  the  in- 
strument. 


Some  observations  were  made  during  the  course  of  the 
experiments  which  will  probably  upset  some  of  the  existing 
conventions  and  increase  the  comfort  of  the  motion  picture 
patrons.  For  instance,  the  black  velvet  frame  which  fre- 
quently surrounds  the  screen  is  found  undesirable  and  a 
neutral  gray  is  suggested  in  its  place.  The  reason  is  simple. 
Suppose  the  illumination  of  the  strongest  highlight  of  the 
picture  is  10  foot  candles.  Under  these  conditions  the 
brightness  of  the  black  velvet  frame  would  be  found  to  be 
about  0.001  foot-candles.  This  makes  the  ratio  of  the  t^vo 
or  the  brightness  contrast  equal  to  1  to  10,000.  This  con- 
trast is  beyond  the  power  of  the  eye  to  record  and  results 
again  in  overtaxing  the  process  of  adaptation.  By  using 
a  material  with  a  higher  reflecting  power  than  black  velvet, 
the  contrast  between  the  screen  and  the  frame  may  be 
brought  within  the  range  of  the  eye.  If  the  brightness  of 
the  frame  is  raised  to  0.02  foot-candles,  the  contrast  between 
the  strongest  highlight  in  the  picture  and  the  frame  is  1  to 
500.  Scientists  say  that  this  is  about  the  limit  of  contrast 
which  the  eye  can  endure  with  comfort.  In  general,  there- 
fore, the  black  velvet  frame  should  not  be  used  but,  in  its 
place,  a  material  which  has  a  reflecting  power  sufficient  to 
raise  the  apparent  brightness  of  the  frame  to  something 
like  0.02  foot-candles. 

The  selection  of  the  material  will  depend  upon  a  num- 
ber of  factors:  the  illumination  of  the  theater  and  the  dis- 
tance of  the  screen  behind  the  front  of  the  stage  being  the 
principal  ones.  For  experimental  purposes  in  the  labora- 
tor\-  it  was  found  that  covering  the  black  frame  with  white 
mill  net  was  quite  satisfactor>\  Such  an  expedient  will  not  in 
general  be  found  satisfacton*-  in  practice  since  this  material 
will  undoubtedly  fail  to  harmonize  with  the  elegance  and 
richness  of  finish  frequently  found  in  the  modern  motion 
picture  theater.  In  many  cases  the  screen  area  is  surrounded 
by  drapings  of  silk,  velvet,  or  other  fabrics  and  in  such 
cases  it  is  suggested  that  a  fabric  harmonizing  with  the 


general  decorative  scheme  be  used  as  a  draping  immediately 
around  the  screen  area,  the  color  that  will  give  a  satisfac- 
tory result  being  such  as  in  ordinary  terminolog>'  is  referred 
to  as  a  rather  dark  gray.  A  very  pleasing  result  was  ob- 
tained in  an  experimental  installation  by  the  use  of  a 
screen  frame  covered  with  a  warm-gray  burlap  such  as  is 
used  for  wall  coverings.  In  case  the  decorative  scheme  is 
carried  out  not  by  the  use  of  fabrics  but  by  the  use  of  painted 
surfaces,  the  frame  should  be  made  by  use  of  a  rather  dark 
gray  paint.  Of  course,  it  should  be  understood  that  in  case 
a  true  gray  does  not  harmonize  well  with  the  decorative 
scheme  of  the  interior  some  rather  dark  color  tone  (includ- 
ing colors  usually  referred  to  as  warm  or  cool  grays)  may 
be  used  with  advantage.  In  any  event,  small  samples  of 
fabric  or  small  panels  painted  with  various  colors  should 
be  tried  by  placing  them  temporarily  in  position  near  the 
screen  and  the  final  choice  made  when  a  material  or  paint 
is  found  having  a  reflecting  power  such  as  to  make  the 
frame  appear  of  the  correct  brightness*. 

For  similar  reasons,  no  area  of  the  interior  of  the  theater 
visible  from  any  seat  in  the  audience  except  the  picture 
itself  should  have  an  apparent  brightness  of  more  than  2.5 


*It  should  be  pointed  out  that  when  a  frame  of  relatively  high 
reflecting  power  is  used,  the  opening  in  the  frame  should  coincide 
exactly  in  shape  and  size  with  the  projected  picture.  In  case  the 
opening  is  slightly  smaller  than  the  projected  picture,  the  overlapping 
at  the  edges  will  naturally  be  much  more  apparent  and  objectionable 
than  when  a  black  frame  is  used.  In  constructing  the  frame,  there- 
fore, care  should  be  taken  to  prevent  the  occurrence  of  this  undesirable 
feature.  Since  it  may  be  somewhat  difficult  in  some  cases  to  establish 
and  maintain  exact  register  of  picture  with  frame  opening,  it  may  be 
well  to  use  a  narrow  border  of  very  dark  gray  immediately  around  the 
picture.  By  using  such  a  border,  which  need  not  exceed  six  inches  in 
width  and  may  be  narrower  if  care  is  exercised,  a  picture  slightly 
larger  than  the  opening  in  the  frame  may  be  used.  A  stripe  of  such 
widths  subtend  such  a  small  angle  at  the  eye  of  the  observer  that  its 
effect  in  producing  disagreeably  high  contrast  will  be  practically 
negligible. 


to  3.0  foot-candles.  This  applies  to  the  walls  near  a  lamp, 
to  the  lamp  itself  if  it  is  not  concealed,  to  any  diffusing 
globes  or  fixtures  used,  and  in  general  to  any  part  of  the 
interior  of  the  theater.  For  example,  a  sheet  of  white  paper 
illuminated  by  a  25  watt  lamp  at  a  distance  of  one  foot, 
has  an  apparent  brightness  of  about  20  foot-candles.  A 
sheet  of  music  illuminated  in  this  way,  if  visible  from  the 
audience,  becomes  a  glare  spot  and  may  cause  great  dis- 
comfort. Arrangements  should  therefore  be  made  which, 
while  providing  adequate  illumination  for  the  musicians, 
will  prevent  the  illuminated  sheets  from  being  visible  to 
the  audience.  Lights  under  a  balcony  are  particularly  bad 
and  should  be  used  only  with  a  properly  designed  indirect 
lighting  system.  Considerable  attention  should  be  paid  to 
the  character  and  position  of  exit  signs.  While  it  is  neces- 
sary to  make  such  signs  very  conspicuous,  this  can  be 
accomplished  without  making  them  so  brilliant  as  to  be- 
come disagreeable  glare  spots. 

The  use  of  a  projection  screen  set  well  back  from  the 
stage  and  shielded  to  a  great  extent  from  light  reflected 
from  the  walls  and  ceiling  would  probably  permit  of  even 
greater  values  of  the  general  interior  illumination  than  used 
in  the  tests  performed  by  the  laboratory.  The  results 
obtained  in  the  tests  indicate  that  the  illumination  should 
be  about  0.1  foot-candles  on  the  table  plane*  near  the 
front  of  the  theater  and  increase  gradually  to  about  0.2 
foot-candles  near  the  back  of  the  theater. 

It  is  suggested  that  if  the  lighting  of  the  vestibule,  lobby 
and  foyer  be  graded  so  that  the  transition  from  the  sun- 
light to  the  interior  of  the  theater  is  made  gradual,  the 
shock  to  the  eyes  on  entering  and  leaving  the  theater  will 
be  diminished.  If  properly  designed,  it  is  possible  that  the 
time  necessary  for  the  adaptation  of  the  eyes  to  the  inter- 

*The  table  plane  is  any  horizontal  surface  30  inches  above  the 
floor.  The  amount  of  illumination  in  a  room  is  usually  specified  by 
measuring  the  illumination  at  the  table  plane  for  a  number  of  difTerent 
points  in  the  room. 


ior  brightness  when  entering  the  theater  will  be  consumed 
in  passing  into  the  theater  so  that  ordinary  print  may  be 
read  at  once.  In  any  case,  it  would  be  unnecessary  to 
equip  the  ushers  with  flashlights  as  is  often  done  at  present. 
A  moving  light  of  this  sort  is  very  annoying,  especially  to 
persons  sitting  close  to  the  aisle. 

The  present  high  efficiency  tungsten  lamps  which  are 
almost  universally  employed  for  theater  illumination  give 
an  effect  which  is  rather  harsh  and  excessi\ely  brilliant. 
This  may  be  overcome  by  choosing  a  color  scheme  for  the 
interior  which  uses  warm  tones.  Another  remedy  is  to 
dip  the  lamps  in  colored  lacquer.  The  formula  below  gives 
a  very  pleasing  amber  color  which  is  quite  satisfactory. 
Other  dye  materials  may  be  used  when  the  amber  color 
does  not  harmonize  with  the  general  color  scheme  of  the 
interior  of  the  theater. 

Formula  for  Dipping  Lamps 

4^2  ounces  Sandarac  (Powdered) 

^2  ounces  Venice  Turpentine 

58      grains  Metanil  Yellow  No.  1955 

(National  Aniline  Co.,  Buffalo.  X.  Y.) 
K  fluid  ounce       Lavender  Oil  (Garden) 
2612  fluid  ounces     Denatured  Alcohol 

In  figure   (I)   is  shown  a  possible  arrangement  of  the 

lighting  in  a  theater  which,  it  is  thought  would  be  very 

satisfactory.    This  plan  is  presented  as  one  way  of  handling 

the  problem  and  many  others  may  be  worked  out.     The 

scheme  is  designed  to  duplicate  as  nearly  as  possible  the 

results  obtained  in  the  laboratory  and  any  scheme  which 

will  do  this  would  work  equally  well.     The  ceiling,  which 

consists  of  four  arches,  is  illuminated  by  lamps  concealed 

in  the  fixtures  as  indicated.    The  total  candle  power  of  the 

lamps  in  each  fixture  is  indicated  by  such  expressions  as 

i  =  Ix,    i^4x,    etc.      Without    knowing    the    size    of    the 

theater,  it  is  quite  impossible  to  specify  the  exact  amount 

of  light  to  be  used.    The  symbols  mean  that  four  times  as 

much  candle-power  should  be  used  at  the  fixture  marked 

i  =  4x  as  at  the  one  marked  i  =  Ix.    Thus,  if  the  size  of  the 


o 

o 

1—1  v5 

.   to 

o  '^ 


theater  made  it  necessary  to  use  100  candle  power  at  i  =  Ix, 
we  should  have  to  use  4  x  100  or  400  candle-power  at  i  =  4x. 
This  will  give  an  illumination  which  is  more  intense  at  the 
back  of  the  theater  and  which  gradually  becomes  less  to- 
ward the  front. 

Since  the  lamps  must  be  placed  comparatively  close  to 
the  ceiling,  it  would  be  necessary  in  order  to  obtain  a  uni- 
form ceiling  brightness  to  arrange  the  decorative  scheme  so 
that  the  region  marked  B  would  have  a  relatively  low  re- 
flecting powder  while  that  marked  A  should  have  a  high 
reflecting  power.  In  general,  it  is  desirable  to  use  a  material 
of  low  reflecting  power  near  the  lighting  fixtures  in  order 
to  cut  down  the  brightness  to  a  point  where  it  will  not 
exceed  3.0  foot-candles. 

Near  the  floor  of  the  theater  in  the  figure  will  be  found 
numbers  indicating  approximately  the  values  of  the  illumi- 
nation at  those  points.  The  expression,  E  =  0.10  means 
that  the  illumination  on  the  table  plane  at  that  point 
should  be  about  0.10  foot-candles.  The  arrangement  of 
the  fixtures  is  such  that  with  the  candle-power  in  each  fix- 
ture indicated,  the  illumination  at  the  table  plane  will  be 
correct.  No  attempt  is  made  here  to  work  out  the  details 
of  the  interior  illumination  and  decoration.  They  depend 
so  much  upon  the  size  of  the  theater  that  each  case  must 
be  considered  separately.  It  is  only  desired  to  show  the 
importance  of  proper  interior  illumination  for  motion  pic- 
ture theaters  and  to  indicate  the  results  that  may  be  ob- 
tained by  co-operation  between  the  designer  and  the  light- 
ing engineer,  making  use  of  the  results  obtained  in  the 
research  laboratory. 

A  complete  and  more  technical  account  of  the  experi- 
ments carried  out  by  the  research  laboratory  can  be  found 
by  consulting  the  list  of  articles  given  at  the  end  of  this 
pamphlet.  The  research  laboratory  is  also  ready  to  co- 
operate at  any  time  in  the  solution  of  problems  which 
may  arise. 

14 


The  Choice  of  a  Suitable  Projection  Screen 

DOES  the  motion  picture  screen  appear  equally  bright 
from  all  angles  of  view?  In  other  words,  does  the 
screen  appear  too  bright  for  persons  in  the  center  of  the 
theater  and  not  bright  enough  for  persons  at  the  side. 
This  was  the  second  phase  of  the  problem  considered  by 
the  Kodak  Research  Laboratory.  Nearly  all  the  projec- 
tion screens  on  the  market  were  examined,  and  such  wide 
differences  between  the  many  types  were  found  that  the 
results  are  being  published  to  make  it  possible  to  choose 
the  screen  which  will  be  suitable  for  the  particular  theater 
in  which  it  is  to  be  used.  It  is  found  that  a  screen  which 
would  be  satisfactory  in  one  theater  might  fail  completely 
in  another.  The  result  of  most  interest  to  motion  picture 
theater  owners  and  managers  is  the  fact  that  it  is  now  pos- 
sible to  select  the  best  screen  for  a  given  theater  with  scien- 
tific accuracy. 

Every  projection  screen  has  its  own  reflection  character- 
sties.  Some  reflect  nearly  all  the  light  in  a  narrow  beam 
giving  plenty  of  light  for  persons  sitting  in  the  center  of 
the  theater  and  almost  none  for  those  at  the  sides.  There 
are  other  screens  which  appear  of  nearly  equal  brightness 
from  any  seat  in  the  theater.  These  represent  extreme 
cases  with  the  majority  of  screens  occupying  an  intermed- 
iate position  between  the  two.  The  choice  of  screen  de- 
pends mainly  upon  the  shape  of  the  theater.  However,  in 
order  to  determine  the  best  screen  for  a  given  theater,  it 
is  first  necessary  to  determine  accurately  the  reflecting 
power  of  the  screens  for  all  angles  of  view. 

This  the  Research  Laboratory  has  done  for  a  number 
of  commercial  screens.  Orders  for  samples  of  projection 
screens  were  placed  with  practically  every  maker  whose 

IS 


advertisement  could  be  located  in  the  trade  journals.  A 
response  was  not  obtained  from  all  the  makers  but  a  fairly 
representative  group  of  samples  was  received.  A  special 
apparatus,  a  gonio-photometer,  was  constructed  for  the 
purpose  of  measuring  the  reflecting  power.  A  beam  of 
light  was  thrown  upon  the  sample  of  screen  perpendicularly, 
thus  illuminating  it  in  very  much  the  same  manner  as  in 
the  motion  picture  theater.  A  small  instrument  which  could 
be  set  to  view  the  screen  from  any  angle  was  used  to  meas- 
ure the  reflecting  power.     (See  Figure  II.)   In  this  wa\'  the 


Fig.  II 
The  Gonio-Photometer  which  was  designed  and  built  by  the  Kodak 
Research  Laboratory  for  the  purpose  of  measuring  the  reflection 
characteristics  of  motion  picture  screens. 

reflecting  power  of  a  screen  could  be  determined  when 
viewed  perpendicularly  or  at  angles  of  5  to  70  degrees  from 
the  perpendicular.  These  \alues  are  given  for  each  screen 
in  Table  IV  of  the  appendix.  This  table  contains  all  the 
necessary  data  for  the  complete  specification  of  the  reflec- 
tion characteristics  of  a  projection  screen. 

Since  we  are  interested  in  having  the  screen  appear  of 
satisfactory  brightness  to  persons  at  the  side  of  the  theater 
as  well  as  in  the  center,  it  is  necessary  to  decide  on  the 
maximum  amount  that  the  reflecting  power  can  fall  off 

16 


before  the  screen  brightness  becomes  insufficient.  Making 
use  of  all  the  existing  data  on  the  subject,  the  laboratory 
staff  decided  that  the  reflecting  power  for  the  persons  sit- 
ting at  the  side  of  the  theater  should  never  be  less  than 
one-fourth  of  the  reflecting  power  for  persons  in  the  center 
of  the  theater.  That  is,  with  the  proper  screen  brightness 
for  persons  in  the  center  of  the  theater,  the  brightness  of 
the  screen  as  seen  by  persons  at  the  side  should  never  be 
less  than  one-fourth  of  the  proper  amount.  If  the  ratio  of 
the  reflecting  powers  is  greater  than  four  to  one,  it  will 
result  in  diminishing  the  number  of  good  seats  in  the  theater. 
Obviously,  a  screen  which  would  give  excellent  results  in 
a  long  narrow  theater  might  not  be  suitable  in  a  very  wide 
theater  where  the  angle  of  view  was  greater. 

The  maximum  angle  of  view  can  be  determined  from 
a  floor  plan  of  the  theater.  It  may  be  found  by  drawing 
a  line  connecting  the  most  extreme  seat  on  the  side  with 
the  center  of  the  screen.  The  angle  of  view  is  then  meas- 
ured between  this  line  and  a  line  drawn  through  the  center 
of  the  theater.  It  will  sometimes  be  found  that  there  are 
a  few  seats  on  the  side  which  will  add  to  the  angle  of  the 
theater  considerably.  If  these  seats  are  usually  vacant,  it 
may  be  undesirable  to  increase  the  angle  for  the  benefit  of 
the  few  persons  who  might  occupy  them.  The  figure  III 
will  illustrate  this.  The  required  angle,  counting  all  seats, 
is  40  degrees.  However,  95  per  cent  of  the  seats  are  con- 
tained within  an  angle  of  30  degrees.  With  the  knowledge 
that  these  seats  will  not  be  as  good,  it  is  sometimes  per- 
missible to  choose  an  angle  which  does  not  include  them. 
The  distortion,  which  no  screen  can  correct,  is  often  more 
annoying  from  the  side  of  the  theater  than  the  falling  off 
of  the  screen  brightness. 

In  selecting  a  screen  for  a  motion  picture  theater,  the 
procedure  should  be  somewhat  as  follows.  First  deter- 
mine from  the  floor  plan,  the  maximum  angle  of  view. 
Let  us  suppose  that  this  angle  is  found  to  be  30  degrees. 

17 


In  table  II  will  be  found  a  list  of  commercial  projection 
screens  and  in  the  second  column  the  maximum  angle  for 
each  screen  is  given.  It  would  be  undesirable  to  use  a 
screen  for  which  the  maximum  angle  is  20  degrees  in  a  30 
degree  theater,  so  we  may  rule  out  the  first  few  screens 


Fig.  Ill 
Floor  plan  of  a  typical  theater  with  an  extreme  angle  of  40  degrees. 
Ninety-five  percent  of  the  seats  lie  within  an  angle  of  30  degrees. 

which  are  listed  as  being  suitable  only  to  an  angle  of  20 
degrees.  It  will  then  be  noticed  that  any  of  the  remaining 
screens  may  be  used  without  exceeding  the  angle  for  which 
they  become  unsatisfactory.  If  there  were  no  other  factors 
to  consider,  the  most  efficient  screen  would  be  the  one 
which  had  the  highest  average  reflecting  power.  The  values 
of  the  average  reflecting  power  will  be  found  in  column  3. 
A  low  reflecting  power  is  undesirable,  since  it  necessitates 
a  larger  electric  current  through  the  arc  of  the  projection 
machine  and,  therefore,  increases  the  cost  of  operation. 

There  are  several  other  factors,  however,  of  as  much 
importance  as  a  high  reflecting  power.  The  texture  and 
color  must  also  be  considered  in  choosing  a  projection 
screen.  These  factors  are  listed  in  columns  four  and  five 
of  Table  II.     It  is,  of  course,  difficult  to  describe  the  color 

IS 


or  texture  in  exact  terms.  Samples,  which  could  be  de- 
scribed by  the  same  terms,  may  appear  very  different  when 
placed  b)^  side  by  side.  Columns  four  and  five  must  be  con- 
sidered, therefore,  as  giving  only  a  general  idea  of  the 
character  of  the  surface  of  the  screen. 

The  laboratory  is  not  in  a  position  to  advise  on  two 
other  factors  which  will  influence  the  choice  of  a  screen; 
namely,  the  durability  and  the  cost.  The  problem,  which 
was  undertaken  by  the  laboratory,  was  to  determine  the 
most  satisfactory  conditions  of  projection,  regardless  of 
their  cost.  It  is  believed,  however,  that  improvements  as 
suggested  by  this  booklet  will  be  soon  paid  for  at  the  box 
ofiice. 

The  Kodak  Company  is  prepared  to  measure  the  re- 
flection characteristics  of  samples  of  motion  picture  screens, 
and  a  testing  department  is  maintained  at  the  research 
laboratory  for  this  purpose.  A  sample  screen  eight  inches 
square  is  required.  The  Company  is  also  ready  at  any 
time  to  co-operate  in  the  choice  of  a  suitable  screen  to  fit 
a  given  theater.  A  nominal  charge  only  is  made  for  such 
services.  All  correspondence  or  samples  of  screens  should 
be  addressed  to  the  Motion  Picture  Film  Department. 


19 


TABLE    I 

No.  Name  of  Screen  Manufacturer 

1 Superlite C.  S.  Wertsner  &.  Son, 

211-221  N.  13th  St., 
Philadelphia,  Pa. 

2 Special " 

3 Green  Back " 

4 White  Back 

5 Plain  White  Coated 

6 Irnsco  Silver  No.   1 Independent  Movie  Supply  Co., 

729  7th  Ave.,  New  York  City 

7 Imsco  Gold  No.  1 " 

8 Imsco  No.  2 

9 Imsco  No.  3 " 

10 Imsco  No.  4 " 

11 Imsco  White  Muslin " 

12 Idealite — Grade  lA Ludcke  Picture  Screen  Co., 

St.  Peter,  Minn. 

13 Idealite— Grade  IB 

14 Idealite— Grade  2 

IS Dalite  Crystal  White Da-Lite  Screen  &  Scenic  Co., 

922  W.  Monroe  St., 
Chicago,  111. 

16 Dalite  Gold  Fiber 

17 Dalite  Silver 

18 Gold  King   Gold   King    Moving    Picture 

Screen    Company, 

327  East  California   St., 

Oklahoma    City,  Okla. 

19 Half-tone Raven  Screen  Company, 

257  So.  2nd  Ave., 
Mt.  Vernon,  N.  Y. 

20 Aluminum  Paper W.  G.  Preddy,  187  Golden  Gate 

Ave.,  San  Francisco,  Calif. 


20 


TABLE    II 

No. 
Fable  I 

Maximum 

Angle 

Average 

Reflecting 

Power 

Color 

Texture 

6 

20° 

218 

Metallic 

White 

Coarse  Grain 

18 

20° 

209 

Metallic 

Yellow 

Smooth 

1 

20° 

205 

Metallic 

White 

Coarse  Grain 

2 

30° 

204 

Metallic 

White 

Coarse  Grain 

7 

30° 

1<S4 

Metallic 

Yellow 

Coarse  Grain 

8 

30° 

165 

Metallic 

White 

Coarse  Grain 

9 

30° 

150 

Aletallic 

White 

Medium  Grain 

17 

30° 

12S 

Metallic 

White 

Fine  Grain 

20 

30° 

96 

Metallic 

White 

Smooth 

3 

40° 

136 

Metallic 

White 

Fine  Grain 

10 

40° 

129 

Metallic 

White 

Fine  Grain 

4 

40° 

121 

Metallic 

White 

Fine  Grain 

13 

50° 

104 

Metallic 

White 

Medium  Grain 

16 

50° 

79 

Metallic 

Yellow 

Fine  Grain 

12 

70° 

92 

Metallic 

White 

Fine  Grain 

14 

70° 

89 

Metallic 

White 

Fine  Grain 

19 

70° 

70 

White 

Smooth 

5 

70° 

69 

Yellow 

Smooth 

15 

70° 

68 

Blue  Green 

Smooth 

11 

70° 

62 

White 

Smooth 

Appendix 

After  measuring  the  reflection  characteristics  of  various 
motion  picture  projection  screens,  it  was  decided  to  examine 
a  number  of  miscellaneous  surfaces.  It  was  thought  that 
an  examination  of  their  characteristics  might  point  the  way 
to  the  manufacture  of  even  better  and  more  efficient  screens 
than  at  present. 

The  results  of  this  examination  are  given  in  Table  III 
which  is  similar  to  Table  II  for  the  commercial  projection 
screens.  It  will  be  noted  that  only  two  of  the  miscellaneous 
surfaces  fall  in  the  20  degree  class  and  the  rest  in  the  70 
degree  class.  The  surfaces  numbered  28  and  29  are  quite 
similar  and  are  not  suited  for  use  beyond  20  degrees.  Num- 
ber 28  is  prepared  by  placing  a  mirror  directly  behind  a 
ground  glass  focusing  screen;  while  number  29  is  a  mirror, 
the  first  surface  of  which  has  been  sand  blasted. 

In  the  70  degree  class,  the  surface  of  chalk  (Magnesium 
Carbonate)  is  the  most  interesting.  The  reflecting  power 
is  high  and  very  nearly  constant  out  to  70  degrees.  It  has 
a  pure  white  color  and  a  surface  which  appears  perfectly 
smooth  to  the  eye.  For  this  reason  scientists  have  adopted 
this  surface  as  the  standard  of  a  diffusely  reflecting  sub- 
stance, although  it  would  naturally  be  unsuited  as  a  pro- 
jection screen. 

The  actual  values  of  the  reflecting  powers  of  all  sub- 
stances are  given  in  Table  IV  for  all  angles  of  observation 
at  which  measurements  were  made.  The  reflecting  power 
was  measured  by  comparing  the  brightness  of  the  surface 
being  examined  to  that  of  a  surface  of  magnesium  carbonate 
viewed  perpendicularly  under  the  same  conditions  of  illum- 
ination. The  reflecting  power  of  the  magnesium  carbonate 
was  assumed  to  be  100  and  the  reflecting  powers  of  the  other 
substances  referred  to  it. 


TABLE    III 


No. 

Maximum 
Angle 

Average 
Reflecting 
Power 

21 

20" 

339 

22 

20° 

305 

23 

70° 

94 

24 

70° 

82 

25 

70° 

75 

26 

70° 

74 

27 

70° 

67 

28 

70° 

62 

29 

70" 

49 

Surface 
Focusing  Screen  and   Mirror 
Sand  blasted  Mirror 
Magnesium  Carbonate  (Chalk) 
Photo-Stock  Coated 
Opal  Glass 

White  Drawing  Paper 
Photo-Stock  Uncoated 
White  Blotting  Paper 
Sand  blasted  Aluminum 


TABLE  IV. 

Angle 


30°  40°  50°  60° 


1 

266 

256 

215 

168 

120 

64.8 

34.3 

21.8 

16.8 

14.2 

2 

300 

284 

255 

206 

167 

93.9 

52.2 

26.5 

17.0 

13.3 

3 

208 

203 

188 

161 

134 

85.0 

63.3 

33.0 

22.4 

18.3 

4 

177 

174 

165 

143 

122 

85.9 

B3.0 

33.0 

23.8 

17.7 

5 

72. 

9 

72 

2 

70 

8 

70 

5 

69.4 

68.9 

68.1 

68.8 

67.0 

64.0 

6 

286 

273 

229 

173 

129 

66.0 

33.0 

21.4 

15.2 

13.7 

7 

311 

288 

234 

180 

125 

66.0 

35.0 

21.7 

15.6 

14.0 

8 

230 

200 

200 

171 

141 

83.1 

47.4 

29.6 

20.3 

16.0 

9 

206 

197 

177 

152 

127 

80.6 

47.9 

34.3 

24.3 

19.9 

10 

186 

183 

169 

146 

120 

79.8 

47.9 

31.3 

22.2 

17.6 

11 

66 

4 

66. 

3 

65 

2 

63 

8 

62.4 

61.0 

60.4 

60.0 

59.3 

58.9 

12 

154 

151 

136 

112 

97.0 

75.1 

56.0 

52.9 

47.0 

43.0 

13 

193 

187 

154 

124 

98.5 

72.2 

58.4 

50.2 

45.2 

40.9 

14 

142 

137 

122 

103 

93.6 

76.4 

63.7 

55.6 

50.8 

46.8 

15 

71. 

7 

71 

7 

70 

8 

69 

9 

69.2 

63.6 

67.1 

66.0 

65.3 

64.8 

16 

126 

120 

116 

104 

90.7 

68.8 

47.1 

34.3 

26.5 

21.9 

a? 

183 

172 

157 

134 

107 

65.0 

42.1 

28.8 

20.9 

16.8 

18 

292 

271 

216 

160 

108 

49.2 

28.4 

17.4 

13.1 

9.7 

19 

78. 

6 

78. 

6 

74 

9 

73 

3 

71.1 

68.6 

65.3 

63.9 

62.3 

59.5 

20 

148 

136 

111 

93 

6 

74.1 

50.2 

34.1 

26.5 

22.6 

19.5 

21 

460 

430 

373 

257 

176 

73.3 

31.9 

20.5 

19.0 

19.4 

22 

473 

399 

297 

224 

121 

62.0 

40.2 

34.2 

32.0 

31.1 

23 

100 

100 

99 

9 

98 

0 

96.9 

94.9 

92.4 

89.5 

84.8 

78.8 

24 

91 

1 

88 

0 

84 

9 

82 

5 

80.5 

79.3 

78.7 

78.7 

76.9 

74.3 

25 

77 

1 

77 

1 

76 

0 

76 

0 

74.8 

73.7 

73.7 

72.6 

70.5 

68.2 

26 

82 

7 

82 

7 

81 

5 

77 

8 

74.4 

72.0 

69.5 

63.3 

67.6 

65.4 

27 

73 

9 

73 

9 

71 

2 

70 

0 

67.0 

65.0 

63.5 

62.2 

61.1 

58.4 

28 

68 

9 

67 

9 

65 

9 

64 

0 

63.0 

60.8 

59.7 

57.2 

64.8 

54.2 

29 

66 

3 

64 

1 

61 

4 

57 

6 

52.4 

46.5 

40.1 

36.0 

35.3 

32.6 

23 


Bibliography 

For  a  more  technical  account  of  the  subject  matter  of 
this  booklet,  the  reader  is  referred  to  the  following  articles 
published  by  members  of  the  staff  of  the  Kodak  research 
laborator}-.  The  Company  has  available  a  limited  number 
of  copies  of  these  articles  and  they  will  be  sent  upon  request 
to  interested  persons.  Please  address  the  request  to  the 
Motion  Picture  Film  Department. 

On  the  Interior  lUuniination  of 
Motion  Picture  Theaters 

Klectrical   Review, 

Vol.  77,  Page  757,  Nov.  13,  1920. 
Tran.sactions  Society  Motion  Picture  Engineers, 

No.  10,  Page  83,  1920. 
Transactions  Illuminating  Engineering  Society, 

Vol.  15,  Page  645,  Dec.  30,  1920. 

On  the  Reflection  Characteristics  of 
Motion  Picture  Screens 

Transactions  Society  Motion   Picture  Engineers, 
No.  11,  Page  .59,  1920. 


E.\sTMAN  Kodak  Company 
Rochester,  N.  V. 


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